Open AccessRecognition of diverse sequences by class I zinc fingers: asymmetries and indirect effects on specificity in the interaction between CF2II and A+T-rich elements.
Author(s) -
Joseph A. Gogos,
Jingmin Jin,
Hong Wan,
Michael Kokkinidis,
Fotis C. Kafatos
Publication year - 1996
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.93.5.2159
Subject(s) - zinc finger nuclease , zinc finger , dna , biology , chloramphenicol acetyltransferase , mutagenesis , binding site , amino acid , genetics , biochemistry , gene , mutant , reporter gene , transcription factor , gene expression
The Drosophila CF2II protein, which contains zinc fingers of the Cys2His2 type and recognizes an A+T-rich sequence, behaves in cell culture as an activator of a reporter chloramphenicol acetyltransferase gene. This activity depends on C-terminal but not N-terminal zinc fingers, as does in vitro DNA binding. By site-specific mutagenesis and binding site selection, we define the critical amino acid-base interactions. Mutations of single amino acid residues at the leading edge of the recognition helix are rarely neutral: many result in a slight change in affinity for the ideal DNA target site; some cause major loss of affinity; and others change specificity for as many as two bases in the target site. Compared to zinc fingers that recognize G+C-rich DNA, CF2II fingers appear to bind to A+T-rich DNA in a generally similar manner, but with additional flexibility and amino acid-base interactions. The results illustrate how zinc fingers may be evolving to recognize an unusually diverse set of DNA sequences.